Well, Jack certainly didn't mind seeing Ianto in such a state of undress. Briefly, he let his gaze skim over the newly exposed skin. No, Jack didn't mind the view right now whatsoever -- even if he was still mostly dressed. That was a condition that could be fast remedied. Very fast, for that matter.
"Mmm... glad to hear that," Jack murmured against Ianto's lips. "I'd have hated to think such a transgression would be, god forbid, permanent." Which would have meant that Jack would have spent time reminding Ianto of certain things. He knew they were coming from two different timelines and Jack felt that pang of longing, wishing he remembered everything Ianto did. But, at least, Ianto wanted this. The rest could be improvised.
"Perhaps," Jack allowed, kissing that smile that graced Ianto's features. Then Ianto moved his hips and in that brief instant, Jack would have given into whatever Ianto asked of him. Power of persuasion through the press of an erection -- Jack heartily approved.
He allowed a chuckle, the noise sounding foreign amidst the soft groans. "No, I suppose I couldn't at that," Jack replied, his face alight. "What I should worry is if one day the student may surpass the master." Jack winced inwardly at his choice of wording. Passing the master, not exactly the visual Jack wanted to conjure for himself. Jack arched his head towards Ianto and that divinely wicked mouth. He would have hated to lose this. Hated.
Lifting his head, Jack gave a responding devilish grin, growing by degrees with each click of the zip as it was lowered. "For a man who presents such an upstanding façade, you have one helluva wicked streak in you, Ianto Jones. The word tease rather jumps to mind."